Filter device and filter element

ABSTRACT

A filter device comprising a filter element ( 9 ), which forms a body extending along a longitudinal axis and can be received in a housing ( 1 ) that can be closed by means of a cover part ( 3 ), a sealing arrangement ( 49 ) being provided in order to form a fluid-tight seal between the housing ( 1 ) and the cover part ( 3 ), is characterized in that the sealing arrangement ( 49 ) as a component of the filter element ( 9 ) is fixed to a sealing carrier ( 48 ) rigidly connected to said element.

The invention relates to a filter device with a filter element, which forms a body extending along the longitudinal axis and which can be received in a housing that can be closed by means of a cover part, a sealing arrangement being provided to form fluid-tight sealing between the housing and the cover part. The invention furthermore relates to a filter element intended for the filter device.

Filter devices for receiving filter elements are readily available on the market in a plurality of embodiments; compare, for example, EP 1 287 871 A1 or EP 0 891 214 B1. In the operation of these filter devices, the filter element must be changed at specific time intervals; this must take place at comparatively short time intervals when there are large volumetric flows to be filtered and/or the fluids are more heavily fouled. In such filter devices, therefore, a design is desirable in which the installation processes for changing the filter elements are simple and uncomplicated, yet reliable sealing between the housing and cover part occurs, even at high pressure levels. To ensure this, it should be noted in each changing process that the sealing arrangement between the cover part and housing is installed correctly, and the attention must be not only on the corresponding sealing element being correctly placed, but also on a sealing element of the type with the correct dimensions being inserted. If installation of the sealing element is forgotten when the elements are being replaced, there is the risk of a malfunction resulting in environmental pollution.

With respect to this problem, the object of the invention is to make available a filter device in which the process of changing the filter element can be carried out especially easily and reliably.

According to the invention, this object is achieved by a filter device having the features of claim 1 in its entirety.

In that, as specified in the characterizing part of claim 1, the sealing arrangement as a component of the filter element is fixed on a seal carrier which is securely connected to it, in the installation processes for changing the filter element the aforementioned error sources are reliably avoided. Since each time the element is changed, the sealing arrangement as a component of the filter element is automatically changed at the same time, not only is the risk avoided that installation of the pertinent sealing element will be inadvertently forgotten, but also the risk that an incorrect sealing element will be installed is avoided. In order to prevent these hazards, in current solutions the procedure is such that an O-ring as an additional part is added to the replacement filter elements; this results in complicating the logistics. Nor does this ensure that the additional part is in fact also installed.

In especially advantageous embodiments the seal carrier is formed by a peripheral part which is radially offset from the central part of the end cap relative to the longitudinal axis, this end cap being provided on the end of the filter element which is associated with the cover part and forming an enclosure for its filter medium.

Preferably the arrangement is such that the peripheral part that forms the seal carrier is connected to the central part of the end cap by way of radially running crosspieces and that the intermediate spaces between the crosspieces in the operating state of the device form fluid passages between a fluid duct in the cover part and the outside of the filter element. In that the seal carrier is connected to the central region of the pertinent end cap solely by way of radial crosspieces, the flow path for fluid entry from the cover part into the interior of the housing is relatively unobstructed.

In preferred embodiments in which the sealing arrangement has an annular body with an inner retaining rib which projects radially inward and which is secured in a peripheral annular groove on the peripheral part of the filter element that forms the seal carrier, the sealing annular body is easily and securely fixed on the seal carrier.

Especially secure retention of the sealing arrangement is ensured in exemplary embodiments in which the sealing arrangement has a profile ring seal with a radially inner recess which is seemingly engaged by a dovetail-shaped outer ring of the peripheral part of the filter element that forms the seal carrier.

Especially reliable sealing is ensured when this profile ring seal has two sealing lips which are opposite one another in the axial direction and which each form one sealing region relative to the cover part and the housing.

The subject matter of the invention is also a filter element for a filter device according to one of claims 1 to 6, the filter element having the features of claim 7 in its entirety.

The invention is detailed below using the drawings.

FIG. 1 shows a longitudinal section of one embodiment of the filter device according to the invention, drawn schematically simplified and on a slightly reduced scale compared to a practical embodiment;

FIG. 2 shows an enlarged partial section of the region designated as X in FIG. 1;

FIG. 3 shows a partial section which is greatly enlarged compared to FIG. 1 and which shows only the head part of a second embodiment, and

FIG. 4 shows a longitudinal section of a third embodiment similar to the figures.

A cup-shaped filter housing 1, which is largely circularly cylindrical and which is closed on the bottom, on its upper end can be closed by a cover part 3 which is detachably joined to the housing 1 via a screw connection 5. The housing 1 can receive a filter element 9 which in a conventional design has a hollow cylindrical filter medium 11, for example in the form of layers of filter mat or a multilayer, folded, or pleated filter body which surrounds a tubular support body 13 which is concentric to the longitudinal axis 2 and which is injection molded from plastic material. The support body, as is most apparent in FIG. 3, has a succession of peripheral circular rings 15 which are spaced apart from one another, of which only a few are numbered in the figures, and which, in the manner which is conventional for these support bodies 13, are connected to a carrier which is located inside and which is made as a star which is three-pointed in cross section, with three points 17. On the end associated with the bottom of the cup of the housing 1 the filter element 9 is closed by a bottom cap 19 of plastic material which forms an enclosure 21 for the filter medium 11. On the opposite end an end cap 23 which is likewise formed from plastic material forms the termination of the filter element 9 facing the cover part 3, the end cap 23 in a similar manner as the bottom cap 19 forming an enclosure 25 for the pertinent end of the filter medium 11.

As can be seen most clearly in FIG. 3, on the radially inside region of the enclosure 25 there is a hollow body 27 which together with an extension 29 which projects axially on the radially inside end of the end cap 23 in the direction to the cover part 3 forms a circularly cylindrical guide 31 in which a sleeve body 33 is guided to be axially displaceable, between the hollow body 27 and the extension 29 a seat being formed for a sealing element 32 which seals the sleeve body 33 relative to the guide 31. The sleeve body 33 is used as a movable coupling part of a connecting means for producing a fluid connection between the filter element 9 and the fluid duct 35 in the cover part 3.

As can be taken from FIG. 1, the fluid duct 35 in the cover part 3 is connected to the fluid outlet 37 for the cleaned fluid. A fluid inlet 39 which is located in the cover part 3 opposite the latter for the fluid to be cleaned is connected in the cover part 3 to a second fluid duct 41, from which the fluid to be cleaned can flow via inflow openings 43 made on the end cap 23 into the annulus 45 which on the outside of the filter medium 11 forms the contaminated side of the filter device, from which the fluid to be cleaned passes through the filter medium 11 from the outside to the inside and reaches the inner filter cavity 47 which forms the clean side. From the inner filter cavity 47 the cleaned fluid travels through the sleeve body 33 which forms the coupling part of the connecting means to the fluid duct 35 of the cover part 3 and thus to the fluid outlet 37.

In the present invention, the sealing arrangement which forms the fluid-tight sealing between the cover part 3 and the housing 1 is a component of the filter element 9. More accurately, the sealing arrangement is permanently fixed on the filter element 9 so that when the filter element is changed, without special effort of the personnel carrying out the changing process, the sealing arrangement is automatically replaced. In these examples the sealing arrangement is tightly joined to the end cap 23 which forms the termination of the filter element on the end associated with the cover part 3. For this purpose, crosspieces 46 are molded in one piece onto the central region 44 of the end cap 23, in these examples six crosspieces 46 which at the same distance from one another project radially relative to the longitudinal axis 2, protruding radially beyond the enclosure 25, and on their outer ends are connected to a ring-shaped peripheral part 48 which is used as the seal carrier on which the sealing arrangement is permanently fixed. The intermediate spaces between the crosspieces 46 on the outside of the central region 44 of the end cap form inflow openings 43 for the entry of the fluid to be cleaned into the filter element 9.

In the example of FIGS. 1 and 2, the sealing element of the sealing arrangement is an annular body 49 which, as is best illustrated in FIG. 2, has a largely square cross sectional shape whose axially opposing surfaces form sealing surfaces for contact with the cover part 3 and the end edge of the opening of the housing 1. As can likewise be clearly seen in FIG. 2, the annular body 49 is fixed on the peripheral part 48 such that a retaining rib 50 which projects radially inward from the annular body 49 is secured in a peripheral annular groove 52 on the peripheral part 48 that forms the seal carrier.

FIG. 3 illustrates one modified embodiment in which the sealing arrangement as the sealing element has a profile ring seal 57 which has sealing lips 59 which are opposite one another, which project out of the essentially rectangular cross sectional shape in the axial direction, and which form the sealing relative to the cover part 3 and the housing 1. This profile ring seal 57 is secured on the peripheral part 48 of the filter element 9 that forms the seal carrier such that an outer ring 55 which projects radially from the peripheral part 48 has a dovetail outline and engages a recess which is likewise dovetail-shaped and which is made inside on the profile ring seal 57, see FIG. 3.

In the embodiments as shown in FIGS. 1 to 3, as the movable coupling part for the fluid connection between the filter cavity 47 which forms the clean side and the fluid duct 35 in the cover part 3, a sleeve body 33 is guided to be axially displaceable within the guide 31. The hollow body 27 which is connected to the end cap 23 and which forms part of the guide 31 on its inner end region has a shape which projects radially inward and which forms a stop shoulder 61 on which one end of a helical compression spring 63 is supported which is supported within the sleeve body 33, adjoining its inside ribs 65 (only a few being numbered in FIG. 3) with its other end on the inner ring shoulder 67 of the sleeve body 33. For the sleeve body 33, this yields pretensioning of the spring for axial motion which extends in the direction to the cover part 3. To limit this motion in the end position, on the extension 29 which forms part of the guide 31 there is a step 69 which constricts the guide and which interacts with a step 70 on the outer periphery of the sleeve body 33 for limiting the end position. FIGS. 1 and 3 which constitute the operating state of the filter device show that when the cover part 3 has been screwed on, the sleeve body 33 is pushed out of the end position against the pretensioning of the compression spring 63 axially into the filter element 9. This is due to the mouth edge 71 of the cover-side fluid duct 35 as the stationary coupling part of the connecting means for forming the coupling connection when the cover part 3 is screwed tight pressing on the sleeve end edge 73 of the sleeve body 33 and pushing it out of the end position, so that the pretensioning of the compression spring 63 is active as sealing force between the mouth edge 71 of the fluid duct 35 and the sleeve end edge 73 of the sleeve body 33. In other words, the coupling connection of the connecting means is automatically established when the device is shifted into the operating state by screwing the cover part 3 onto the housing 1 containing the pertinent filter element 9.

The interacting regions of the sleeve body 33 and the fluid duct 35, which in the coupling state form the sealing, are made such that one of the annular surfaces which are pressed against one another by the pretensioning of the spring forms a continuous radial plane while the other ring surface forms a radial plane with a sealing edge which projects out of it. In these embodiments, the ring surface 75 on the fluid duct 35 is continuously level, while the ring surface 77 along its peripheral edge forms a slightly projecting sealing edge 79. The latter with the radially outer edge of the ring surface 75 forms a seal not only in interaction with its surface edge, but by the edge enclosure of the mouth edge 71 of the fluid duct 35 also forms centering by means of which, when the cover part 3 is screwed on, it is ensured that high-precision alignment of the coupling connection of the connection means necessarily takes place. Considering that the filter element 9, aside from the compression spring 63, can be made without metal, so that mechanical or thermal effects could lead to slight deformations, this centering constitutes an extremely advantageous contribution to the operating reliability of the device.

In the described design of the coupling device, the spring-loaded sleeve body 33 also forms the movable valve body of a bypass valve. When a pressure difference rises, i.e., when the pressure difference between the space between the steps 69 and 70 on the extension 39 and the sleeve body 33 and the inner filter cavity 47 rises to a threshold valve, the sleeve body 33 moves against the force of the spring 63 so that between the ring surface 75 on the end edge 73 of the sleeve and the mouth edge 71 there is a distance between the ring surfaces 75 and 77, that is, a direct connection is formed between the fluid duct 41 and the fluid duct 35 in the cover part 3.

FIG. 4 illustrates another exemplary embodiment without the bypass valve integrated into it. While in the above described embodiments the fluid connection between the filter cavity 47 which forms the clean side and the fluid duct 35 in the cover part 3 takes place by way of an axially movable coupling part which is formed by the sleeve body 33 which is guided to be axially displaceable in the central part 44 of the end cap 23, in the example of FIG. 4, the axial extension 29 of the end cap 23 forms the end-side sealing surface, i.e., the mouth edge 72 of the extension 29 assumes the function of the sleeve end edge 73 of the sleeve body 33 of the above described embodiments. Accordingly, the end edge of the extension 29 on the end side has a ring surface 76 which is not continuously even corresponding to the ring surface 77 in the above described examples, but forms a slightly projecting sealing edge 79 along its peripheral edge. The sealing edge interacts to form a seal with the ring surface 74 which on the mouth edge of the fluid duct 35 is made continuously even. With the cover part 3 screwed on, thus by the interaction of the ring surfaces 74 and 76 as well as the projecting sealing edge 79 (the latter not being shown in FIG. 4), sealing on the fluid connection is formed. Otherwise, the embodiment from FIG. 4, particularly with regard to the sealing arrangement which forms a component of the filter element 9, corresponds to the above described examples. 

1. A filter device with a filter element (9), which forms a body extending along the longitudinal axis (2) and which can be received in a housing (1) that can be closed by means of a cover part (3), a sealing arrangement (49, 57) being provided to form fluid-tight sealing between the housing (1) and the cover part (3), characterized in that the sealing arrangement (49, 57) as a component of the filter element (9) is fixed on a seal carrier (48) which is securely connected to it.
 2. The filter device according to claim 1, characterized in that the seal carrier is formed by a peripheral part (48) which is radially offset from the central part (44) of the end cap (23) relative to the longitudinal axis (2), and this end cap (23), on the end of the filter element (9) which is associated with the cover part (3), forms an enclosure for its filter medium (11).
 3. The filter device according to claim 2, characterized in that the peripheral part (48) that forms the seal carrier is connected to the central part (44) of the end cap (23) by way of radially running crosspieces (46) and that the intermediate spaces between the crosspieces (46) in the operating state of the device form fluid passages (43) between a fluid duct (41) in the cover part (3) and the outside of the filter element (9).
 4. The filter device according to claim 1, characterized in that the sealing arrangement has an annular body (49) with an inner retaining rib (50) which projects radially inward and which is secured in a peripheral annular groove (52) on the peripheral part (48) of the filter element (9) that forms the seal carrier.
 5. The filter device according to claim 1, characterized in that the sealing arrangement has a profile ring seal (57) with a radially inner recess which is securingly engaged by a dovetail-shaped outer ring (55) of the peripheral part (48) of the filter element (9) that forms the seal carrier.
 6. The filter device according to claim 5, characterized in that the profile ring seal (57) has two lips (59) which are opposite one another in the axial direction and which each form a sealing region relative to the cover part (3) and the housing (1).
 7. A filter element for a filter device according to claim 1, which can be received in a housing (1) that can be closed by means of a cover part (3), the sealing arrangement (49, 57) being designed to form fluid-tight sealing between the housing (1) and the cover part (3), characterized in that the filter element (9) together with the sealing arrangement (49, 57), which is fixed on it, form a unit. 